5. Tongue
Oral cavity regional relationships * Superior: Hard palate, maxillary alveolar ridge * Lateral: Cheek-buccal space * Inferior: Mylohyoid muscle (floor of mouth), mandibular alveolar ridge, and teeth * Posterior: Soft palate, anterior tonsillar pillars, & lingual tonsil (tongue base) Tongue * Oral tongue: Anterior 2/3 of tongue * Base of tongue: Posterior 1/3 in the oropharynx * Root of tongue: Undersurface of oral tongue at its junction with anterior floor of mouth and mandible. Deep muscles of oral tongue (genioglossus and geniohyoid) + lingual septum * Floor of mouth: Crescent-shaped region of mucosa overlying mylohyoid and hyoglossus muscles, extending from inner aspect of lower alveolar ridge to undersurface of anterior oral tongue Oral tongue: Extrinsic tongue muscles * Genioglossus: Large, fan-shaped muscle lying parallel to lingual septum ** Origin (O): Upper genial tubercle & internal surface of symphysis menti of mandible ** Insertion (I): Along length of tongue under surface ** Function (F): Protrudes tongue ** Innervation (N): CN12 * Hyoglossus: Thin, quadrilateral-shaped muscle ** O: Body & greater cornu of hyoid bone ** I: Passes vertically to insert into side of tongue ** F: Depresses tongue ** N: CN12 * Styloglossus ** O: Styloid process & stylomandibular ligament ** I: Side of tongue, merges with hyoglossus ** F: Retracts tongue upward & backward ** N: CN12 * Palatoglossus ** O: Undersurface of palatine aponeurosis ** I: Side and dorsum of tongue ** F: Forms anterior tonsillar pillar ** N: CN10, pharyngeal plexus branch * Mylohyoid muscle ** Forms floor of mouth; separates lower OC into SMS and SLS except along posterior margin ** Mylohyoid cleft at junction of anterior 1/3 and posterior 2/3 of mylohyoid muscle *** Contains fat ± vessels ± accessory salivary tissue ** O: Arises from mylohyoid line of mandible ** I: Hyoid bone ** F: Depresses mandible, elevates hyoid bone, OC floor, & tongue ** N: Mylohyoid nerve branch from CNV3 * Oral mucosal space/surface ** Lines entire oral cavity including buccal (cheeks), gingival (gums), palatal, and lingual surfaces * Pterygomandibular raphe ** Fibrous band extending from posterior mandibular mylohyoid line to medial pterygoid plate hamulus ** Buccindfdfator and superior pharyngeal constrictor meet at pterygomandibular raphe ** Lies beneath mucosa of retromolar trigone ** Perifascial route of spread for SCCa from retromolar trigone to base pterygoid plates Innervation of tongue * Sensory supply (touch, pain, temperature and taste) ** Anterior 2/3: Lingual nerve (taste fibers are from chorda tympani branch of CN7) ** Posterior 1/3: CN9 * Hypoglossal nerve (CN12) ** Emerges from nasopharyngeal carotid space ** Receives fibers from 1st and 2nd cervical nerves ** Loops inferiorly to level of hyoid bone ** Rises anteriorly to enter posterior sublingual space just lateral to hyoglossus muscle ** Runs in sublingual space on lateral surface of genioglossus muscle ** Innervates extrinsic and intrinsic tongue muscles Vasculature of tongue * Lingual artery: 2nd branch of external carotid artery ** Divides in sublingual space into sublingual and deep lingual branches * Lingual vein: Parallels lingual artery; drains into internal jugular or facial veins Oral tongue lymph vessels * Two systems: Superficial mucosa and deep collecting * Superficial system: Crossing vessels in anterior floor of mouth drain bilaterally into anterior submandibular nodes * Deep collecting system: Drain into ipsilateral anterior submandibular nodal chain only